Good question, at this point Ben, its just us I know a guy on FB he made some out of scale coal made from recycled car tires.
I finally got back into my PhotoBucket and uploaded my pics of my coal porter. Here are some photos I have collected from EBAY sales plus some of my own. The first three pics from the EBAY ad were of one car converted to scale wheels with Kadee couplers. If you notice closely the draft box does not come apart easily. I called Des Plaines Hobbies and one of the gentlemen recommended placing the car in the freezer for 30-40 mins to permit the superglue holding the draftbox cover on to become brittle and facilitate prying off the cover with a small screwdriver. From that point the typical SSA AF coupler can be removed. I have not tried one yet but hope to someday convert all of them to Kadee couplers.
The cars I ordered in come with AF couplers and hi-rail and scale wheels. The SSA quality is really good.